. 2021 Feb;34(1):67–72. doi: 10.2337/ds19-0068

TABLE 1.

Supplements for Diabetes

	Studied Dose	Safety*	Efficacy*	Comments
α-Lipoic acid	300–1,800 mg daily PO	Possibly safe	Possibly effective	May decrease effectiveness of thyroid hormone
α-Lipoic acid	300–1,800 mg daily PO	SE: GI upset, headache, skin rash	Possibly effective	May decrease effectiveness of thyroid hormone
Berberine	0.9–1.5 g daily PO	Possibly safe	Possibly effective	Avoid if pregnant because of uterine stimulant effects; antiplatelet effects; drug interactions (CY P2C9, CY P2D6, CY P3A4)
Berberine	0.9–1.5 g daily PO	SE: GI upset	Possibly effective
Bitter melon	2–4 g daily	Possibly safe	Insufficient reliable evidence	Avoid if G6PD deficient because of increased risk of favism
Bitter melon	2–4 g daily	SE: GI upset, headache, dizziness	Insufficient reliable evidence	Avoid if G6PD deficient because of increased risk of favism
Chromium	200–1,000 μg daily PO	Possibly safe	Possibly effective	Caution if kidney or liver issues present
Chromium	200–1,000 μg daily PO	SE: GI upset, headache, mood changes	Possibly effective	Caution if kidney or liver issues present
Cinnamon	120–6,000 mg daily PO	Likely safe	Possibly effective	Unsafe in higher doses; caution if taking warfarin or liver issues present; drug interactions (CY P2C9, CY P3A4, CY P2A6, CY P2D)
		Generally
		well tolerated
Fenugreek	5–100 g daily PO added to 1–2 meals/day	Possibly safe	Possibly effective	Avoid if pregnant due to uterine stimulant effects
Fenugreek	5–100 g daily PO added to 1–2 meals/day	SE: GI upset	Possibly effective	Avoid if pregnant due to uterine stimulant effects
Flaxseed	10–60 g daily PO	Likely safe	Possibly effective; effects highest with whole flaxseed	Caution with hormone-sensitive cancers (e.g., breast cancer)
Flaxseed	10–60 g daily PO	SE: GI upset	Possibly effective; effects highest with whole flaxseed
Ginseng	3,000–9,000 mg PO up to 2 hours before a meal; no added benefit found to taking >3,000 mg	Likely safe	Possibly effective	Avoid if taking warfarin
Ginseng		SE: headaches	Possibly effective	Avoid if taking warfarin
Gymnema	250–500 mg twice daily	Possibly safe	Insufficient reliable evidence	Drug interactions (CY P1A2, CY P3A4, CY P2C9)
Gymnema	250–500 mg twice daily	SE: drug-induced hepatitis (rare)	Insufficient reliable evidence	Drug interactions (CY P1A2, CY P3A4, CY P2C9)
Ivy gourd	1–20 g daily	Possibly safe	Possibly effective	Insufficient reliable information available on toxicology
Ivy gourd	1–20 g daily	SE: none reported	Possibly effective	Insufficient reliable information available on toxicology
Prickly pear cactus	300–500 g daily	Possibly safe	Possibly effective	Usually studied as single doses; unknown whether extended daily use can lower glucose levels
Prickly pear cactus	300–500 g daily	SE: GI upset	Possibly effective

*Ratings published in the Natural Medicines database (https://naturalmedicines.therapeuticresearch.com). G6PD, glucose-6-phosphate dehydrogenase; PO, orally; SE, side effects.